Hypoxia inducible factors bound to DNA, molecular model. Hypoxia inducible factors (HIF) proteins bind to DNA (deoxyribonucleic acid) and regulate physiological responses to low oxygen stress. HIF (pink surface) and aryl hydrocarbon receptor nuclear translocator (ARNT, purple surface) combine and bind to the hypoxia response element (HRE) section of DNA (double helix stick model). HIFs coordinate cellular adaptations to low oxygen stress by regulating gene transcription activity.